The most significant ranges in this area are
the Spenser Mountains, with their extensions to the north-east
in Nelson Lakes National Park (Ella, Travers, St Arnaud Ranges),
and further east with the Raglan Range.
These mountains are young and, like the rest
of the Southern Alps, rise sharply east of the Alpine
Fault, which is traced here on the northern border of Nelson
Lakes National Park and in the Wairau Valley. The rate of uplift
and level of precipitation, and consequently also the rate of
erosion, are markedly lower than further west in the axial zone.
Four factors combine in these mountains to generate
a marked sense of uniformity, especially in the Spencer and
Nelson Lakes National Park mountains:
- rock type is almost uniformly greywacke,
- similarity of altitude of summits and crests, typically
2200-2300 m (7218-7546'),
- deep U-shaped valleys and widespread glacial landforms,
- north-south to north-northeast-south-south-west orientation
of most valleys.
Tthe beech forests which extensively cover valley
floors and mountain slopes add to this uniformity. All four
species of southern beech (Nothofagus) are present. The
treeline makes a particularly striking feature in the landscape,
extending in a straight and even line, as if artificially drawn,
along mountain sides at about 1400 m (4593') (cf. photo at top
of page).
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